Power windows, once available on only expensive automobiles or as an expensive option on some automobiles, have become extremely popular. Advances in motor design partly explain their popularity. Smaller motor designs have made it possible to install a compact, inexpensive motor and window gear system, known as the "regulator", into the small narrow door found on many smaller automobiles. Greater consumer affluence may also be a contibuting factor to the popularity of power windows. But even so, the cost for power windows as a percentage of total vehicle cost has become relatively insignificant compared to what is was ten or twenty years ago, so much so, that manufacturers often include power windows in standard power option packages on relatively inexpensive automobiles.
The typical power window moves the window smoothly and rapidly compared to the "old" crank handle. The typical power window system is designed so that a button must be pressed while the window operates, a safety arrangement intended to reduce reaction time when stopping window movement if limb lies in the window's path as it closes. In a seeming clash of goals, the force exerted by the window must be sufficient to overcome ice and adequately compress the window seal, but the window drive should be incapable of exerting damaging pressure on a limb caught between the moving window and the seal. Some systems, addressing this problem, monitor motor current: sensing an overcurrent condition due to a high load the motor is reversed. This approach does not provide precise window motion control.
Over time, window frame and seal (gasket) geometries can change, producing air leaks between the window and the seal. Driving the window hard against the seal can compensate for that but also increases the force applied to objects in the window's path.